66954555809 has 16 divisors (see below), whose sum is σ = 68699461584. Its totient is φ = 65231308800.

The previous prime is 66954555769. The next prime is 66954555839. The reversal of 66954555809 is 90855545966.

It can be written as a sum of positive squares in 8 ways, for example, as 25327131025 + 41627424784 = 159145^2 + 204028^2 .

It is a cyclic number.

It is not a de Polignac number, because 66954555809 - 2²⁰ = 66953507233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66954555839) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17375327 + ... + 17379179.

It is an arithmetic number, because the mean of its divisors is an integer number (4293716349).

Almost surely, 2^66954555809 is an apocalyptic number.

It is an amenable number.

66954555809 is a deficient number, since it is larger than the sum of its proper divisors (1744905775).

66954555809 is a wasteful number, since it uses less digits than its factorization.

66954555809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6548.

The product of its (nonzero) digits is 58320000, while the sum is 62.

The spelling of 66954555809 in words is "sixty-six billion, nine hundred fifty-four million, five hundred fifty-five thousand, eight hundred nine".